JSON: How to check schema in PHP - php

Question

I am a newbie. I am trying to make some experience about REST applications in PHP. So I receive (POST) a JSON body and store the value in my database. I just want to make a check if the JSON body I get is in the right way, if it matches the particular schema I set. I need something like this (for example):
my schema:
{"id":"int",
"name":"string",
"value":"double"
}
I just want to check that my JSON body contains the same fields and types. Thanks in advance.
UPDATE
Thanks to all for your answers. I'd like to follow krichprollsch's answer. It's exactly what I need. So I am using Ubuntu 12.04 LTS and NGINX server. I only installed HttpFoundation and Validator components via Composer. Now in my "www" folder I have a folder called "vendor" where Symfony's components are (I don't know if this folder has to be there). In order to check I made a script taken from some examples on the web but I've got a "500 Internal Server Error". The script is this:
<?php
require 'vendor/autoload.php';
use Symfony\Component\Validator\Validation;
use Symfony\Component\Validator\Constraints\Lenght;
class user{
public function utente(){
$validator = Validation::createValidator();
$violations = $validator->validateValue('Bernhard', new Lenght(array('min'=>10)));
echo $violations;
}
}
$a = new user;
$a->utente();
?>
Any suggestions? Thanks

Answer 1

You can use the Symfony Validator component to validate the data from the json according with your schema : http://symfony.com/doc/master/book/validation.html
<?php
use Symfony\Component\Validator\Constraints as Assert;
use Symfony\Component\Validator\Validation;
//...
$collectionConstraint = new Assert\Collection(
array(
'id' => new Assert\Type(array('type'=>'integer')),
'name' => new Assert\Type(array('type'=>'string')),
'value' => new Assert\Type(array('type'=>'double'))
)
);
//...
$data = json_decode($your_json);
$validator = Validation::createValidator();
$errorList = $validator->validateValue($data, $collectionConstraint);
Using Symfony validator allow you to check complex constraints, not only type of data.
You can also directly validate an hydrated object. Useful if you want to insert into database.

Answer 2

You want chek value???
YOu can decode json strings with json_decode() function.
For example:
$json = {"id":"int",
"name":"string",
"value":"double"
};
$decode = json_decode($json);
if($decode->value == 'Your value') {
//your code
} else {
echo 'Incorerct!';
}

Answer 3

Hey You can decode you json by php
using json_decode function
$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';
$array1 = json_decode($json, true);// it will return an array
for more about json_decode http://in2.php.net/json_decode
and can compare your data structure array ($array2) with this array
by intersecting them.
$result = array_intersect($array1, $array2);
print_r($result);

Answer 4

You can use json_decode to check if it is a valid syntax
$json = '{"id":"int",
"name":"string",
"value":"double"
}';
$decoded = json_decode($json, true);
if($decoded == null){
//your error message
echo "Error in JSON Format";
}
if the string is not valid, json_decode will return a null value